Field of the Disclosure
The present disclosure relates to control device and a corresponding control method for use in a broadcast system. Further, the present disclosure relates to a broadcast system.
The present invention relates, for instance, to the field of Digital Video Broadcasting (DVB) utilizing Orthogonal Frequency Division Multiplexing (OFDM). Further, the present invention can be applied in other systems, such as a DAB (Digital Audio Broadcasting), DRM, MediaFlo, ISDB, ATSC (e.g. 3.0) or LTE broadcast system.
Description of Related Art
The transmission parameters of known broadcast systems, such as the broadcast systems in accordance with the DVB-T2 standard (second generation digital terrestrial television broadcast systems standard), are generally optimized for fixed reception with stationary receivers, e.g. with roof-top antennas. In future broadcast systems, such as the upcoming DVB-NGH (DVB Next Generation Handheld; in the following also referred to as NGH) standard, a mobile receiver (which is the main focus of this upcoming standard) shall be enabled to receive data correctly also in bad reception situations, e.g. despite suffering from multipath propagation, fading effects and Doppler shifts. Such broadcast systems are particularly characterized by the fact that there is generally no feedback channel and no signalling from receivers to transmitters.
A receiver for receiving data in a broadcast system by which the probability of error-free reception/reconstruction of data by a mobile receiver is increased compared to receivers in known broadcast systems, even under bad reception conditions, is disclosed in WO 2011/080020 A1. The disclosed receiver comprises                a broadcast receiver unit for receiving from said broadcast system a receiver input data stream segmented into frames, wherein basic codeword portions of codewords are mapped onto said frames, a codeword comprising said at least a basic codeword portion generated from an input data word according to a first code,        a data demapper for demapping the basic codeword portions from said frames of the receiver input data stream,        a decoder for error correction code decoding said codewords into output data words of at least one output data stream in a regular decoding step by use of the basic codeword portion comprised in a codeword,        a check unit for checking if the regular decoding of a codeword is erroneous,        a unicast request unit for requesting, if said regular decoding of a codeword is erroneous, through a unicast system an auxiliary codeword portion of the erroneously decoded codeword for use as incremental redundancy in an additional decoding step,        a unicast receiver unit for receiving from said unicast system an auxiliary codeword portion of the erroneously decoded codeword,wherein said decoder is adapted to decode the respective codeword again in an additional decoding step by additionally using the received auxiliary codeword portion, and        a data output for outputting said at least one receiver output data stream segmented into said decoded output data words.        
The main use of redundancy data is the increase of the coverage area for terrestrial broadcasting. Subscribers located at the edge of the coverage area of a broadcast system (also called broadcast network) are suffering from low receptions levels, which may hinder error-free decoding. This is also true for indoor reception or if large objects attenuate the transmitted signal. To counter this problem the utilization of a (wired or wireless) broadband system (also called broadband network) for providing additional redundancy for enabling error-free reception has been proposed. In many cases only a few dBs received signal level are missing for the correct demodulation and decoding of the broadcast data, resulting in an additional redundancy data stream of few hundred kbit/s. Furthermore other channel impairments like burst noise or narrowband interferer create decoding errors in a sheer broadcast reception scenario which are corrected with the additional redundancy data stream.
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventor(s), to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.